Makefile: suppress error messages from 'git'.

If you have a clone of the 'wiggle' git tree but with no
tags, then "git describe HEAD" will complain
   fatal: No names found, cannot describe anything.
As it produces no output, the compiled in default will be used
so this is just an unnecessary message.  So send it to /dev/null.

Reported-by: Stephen Cameron @ G+
Signed-off-by: NeilBrown <neilb@suse.de>
vpatch: avoid warning from gcc-4.4.6

It seems that gcc-4.4.6 doesn't like

   struct plist p = {0};

as it don't initialise all fields.
I only added that to make sure 'outfile' was initialised, so
just do that explicitly.

Reported-by: Stephen Cameron @ G+
Signed-off-by: NeilBrown <neilb@suse.de>
vpatch: change free_stuff to a macro for proper c
vpatch: change find_line to a macro for proper c
vpatch: change prepare_merge to a macro for proper c
makefile: add -Wno-missing-field-initializers since {0} is valid C99
Merge branch 'master' of https://github.com/seanfarley/wiggle